1. Field of the Invention
The present invention relates to manually operated liquid dispensing pump devices for use with consumer product containers; and more particularly, to such devices having a collapsible pump chambers (e.g., a bellows pump chamber) which perform multiple functions.
2. Description of the Prior Art
Manually operated dispensing devices for pumping liquid from a supply container are widely known in the art. These liquid dispensers traditionally utilize a piston and cylinder pump chamber. A helical metal spring is generally utilized to provide the force necessary to return the piston to its initial position. Additional parts are generally related to an inlet valve, an outlet valve and a vent valve. Furthermore, in cases where a liquid spray discharge is desired, additional parts are often related to a swirl chamber. One disadvantage of such piston and cylinder dispensing devices is the great amount of sliding friction developed between the piston and the cylinder due to the tight telescopic fit required to maintain a fluid tight seal. Binding, may also occur between the piston and cylinder. Another disadvantage includes the relatively large number of parts such sprayers typically utilize which generally increases the cost of such pumps.
Consequently, attempts to utilize a manually compressible flexible pump chamber in place of the piston and cylinder have been made. For example, bellows have been utilized to replace the function of the piston, cylinder and return spring. Still other liquid dispensing devices have utilized a diaphragm or bladder as the manually compressible pump chamber. The use of such manually compressible pump chambers is substantially free of friction and the potential binding losses associated with the piston and cylinder. Some of these pump devices have integrally molded duckbill, flapper and/or annular sealing valves with the pump chamber. One disadvantage in the use of such valves is that they do not readily enable the further integral molding of additional functions. Thus, additional parts are generally required; thereby increasing the cost of the pump device. Furthermore, the integral molding of reliable valves can be difficult.